Nearly 2 million people die annually due to indoor air pollution from solid biomass combustion and 99 percent of these deaths are in developing countries. Biomass combustion is a leading risk factor in acute respiratory infections (ARI) and Chronic Obstructive Pulmonary Disease (COPD), especially among women and children. Inefficient combustion of solid biomass leads to 400,000 annual premature deaths in India alone. Studies suggest that biomass combustion is an even greater risk factor for COPD than smoking, particularly in India where 156 million households still depend on solid biomass for cooking and heating. Clean - high efficiency and low emissions - cookstoves offer a solution to this public health challenge, but their uptake and prolonged use have been disappointing. Although more efficient and emissions-reducing stoves can be produced in the laboratory, designing them to meet the needs of users in various social, economic, cultural, and community contexts has proved challenging. Our pilot R21 study will facilitate a subsequent RO1 proposal focused on sustained and effective use of clean cookstoves by rural households, their effect on real time indoor emissions, and on resulting changes in the respiratory health of rural women and children. In this pilot, we will implement a two-year cluster-randomized trial to evaluate factors that enable and hinder sustained use of clean cookstove technologies. The study will compare the effect of traditional wood burning stoves (the control condition) to that of improved wood burning stoves on the respiratory health of women and children. We will implement this study in 120 households in Andhra Pradesh and Rajasthan, India. Our team of investigators comes from medicine, biostatistics, engineering, and social science with a strong transdisciplinary approach to examining barriers to improved cookstove use and with substantial experience doing research in rural India. The specific aims of this R21 are: 1) Evaluate factors which enable and hinder sustained use of clean cookstove technologies by the rural poor in India so we can develop a more refined pivotal intervention focused on improving respiratory health. 2) To generate effect size data that establish the feasibility and inform the sample size o a pivotal trial whose primary objective will be sustained improvements in the respiratory health (measured by FEV1) of women and children in rural India. 3) To generate preliminary emissions data (particulate matter - mass and surface area based, CO, SOX) from clean cookstove technology and its effect on respiratory health outcomes that will facilitate the development of a pivotal clean cookstove intervention. In achieving these aims, we will then have necessary preliminary data to proceed with a larger scale RO1 intervention to examine the effect of sustained use of clean cookstoves and respiratory health outcomes in women and children due to reduced indoor air pollution in rural India. Our study and research program are aligned with the NIEHS and Global Alliance for Clean Cookstoves' mission to address the health of women and children through effective use of clean and efficient cookstove technologies worldwide.